Device for gauging or testing dimensions



July 6,1926. 1,591,349

A. C. WICKMAN DEVICE FOR QAUGING 0R TESTING DIMENSIONS Filed'August 13, 1923 3 Sheets-Sheet 1 A. c. WICKMAN DEVICE FOR GAUGING OR TESTING PIMENSIONS Filed August 13; lss s Sheets-Sheet z July 6,1926; 4 1,591,349

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July 6,1926. v 1,591,349-

A. c. WICKMAN v DEVICE FOR GAUGING 0R TESTING DIMENSIONS Filed August 13; 192: 3 sheets sheet 5 ing Patented July 6,

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The present 'lhvefifci'efl-relates to g- Lhging 011 fes'tmg the ere-curacy. of-the Cll'VlSIGlI of en imaginary ore etifeil circle '0?! other :endleesr hne' en 01 in en'ertlcle l-IItO" parts efr ,QhVlSlOl'lS' intended tel-he equah. is iefeneten'eehhe gauging 'or'testihg of the pteh iiq toqthed Wheelsend fhe like endjchxrismons of 21 de ine head or plate: 91; 01 a SCH-5164113)} 01 :the

,Heretefor'e 'in I op'e'i'ations: there: has been used; a "mister 1 like device iii whie'huewei'm 61' serew thread is empl'oyed whereby the Work 311918 been ltxii'he'd or moved, relatively to the; dial firyhke 5 devices by which variatien; in the dimens-iorivofflle'piteh 0 dwis-lh he's-been lhcheated. Inthis wayfa ehryerhas beem lemed which: if the lfiaeteffworm Wheel or/and. Worm orscrlewthreed 61* lndilca'fl ng devices were ebeolutely pelfecfi would the 'jtre'e erroi' eerie Ofthe rdiv-ieibne bemg gauged 0r testedbht. suchhhebrejtic mlly Ioerfechde- ,vices eminot be produed by means h eretojfbre knbwn and'therei' ere the curve refer-red to has: never heefl correct, ehdconsequently *s'ione'f'dia-ls er Scales 01* E119 like isnet @11- divisi'oh of en ectuelor i111e g'i; ha-1 y eii'de or either endless line; inteperts e1" divisions intended 'i'to beiequelais performed essentially by Zka'xoi'zingt-he beginning ofe 'dfivi sieh and noting, the limiter Etermihfitioh 01? its dineefi sion for putpbses ef eemperisen, zex eiz ag the beg-inning of 'the -hext diyi-sion tethe samezere. and;theneeeerta-iningkthe; degree Ief variation, if any, 'of :-the; dimension eff that;

division "3S compahed I with the dimension ef the preceding --'divi-'s'i(ih endlap'erformin g this operation on each otheradivisien in suecef se s-ionend thus aspertai-n-ingjthe rate ofeha' -ge of ern'er vJalrroughout the Series of divisions. The 'tr u'e el'ro throu gheu-tjthe series if desired, may then {he eseerteined by calcula- 1 en .Ihe Kwrveflr; di re d -b-y plotting. use were he gauged;or f-ested, the zeli her testing ofthet chi i s ien as here desenbed, In other means ecceyd mg t the device by which .the comparative rd nehs cation as mi ht-be: afforded by emicrometerlike device in which a-screwfoi' worm Wheel isemployed is a-Veided, I r 7 Amethod of gaugingor testing ace'Ord-in'g tecting device whereby the hegilnni ngj efeaeh 60 fnethe present inventien mey heperformed 1 by the use" "of a loeatmg, indicating, or cle' time an indieetingef detecting device is I pziratiij'e variation, if any; effthe c1 {heating or dete'ct lnjg device lie-gee ize the beginning pf the DGiXtfidlVlSlOh While the-indicating er cletee H I -,re i"ei1 ed togishs'ecl t9 'eseertein "the eempe ti ve 'a nesi' if-eny'; sfthi so 9 lnsu e wnall l k nchcatmg jot dete'et mj cemparetiveerietieh in; phl e siemvif 21-115,

is escertainecl l ey be suc h tfl m t flieve may be indicated by the userl hiy 55 m marks on squared papelgfeerd; for the like end if these poihts or maths qhe eohhecfted 7 one iththe-nexthy ii esepied ueed' which'i dieatee tiieyiete v of Change 0f erren; qFrom thls rete ofehange of 3* or diagram; a diagram :ereuxweie f true e nor 7 fOIfm-ity qr otherwise pit hef Mheh its-simplest fqrrndne yeonsist ess 61f "ed t'o-engage-e1"to berengaged i1 the between the teeth and se definl-tehbeglnnmg of eeehechv ion for invention beth the zenoiz i r g .cley

of thediVisi may gauged may v,

mhlti plyihglevers p1 ether 1 "d'e ic es by 7 1h ije h lateral movement of the stylus jmeyhe 1111 1 51- inadjeee t; recesses in :thBQW OIk each end bearm g ega nst the sides Qt; file teeth ,a-t eboutthepiteh circle; Olie tleio ie eez ice he species of epiing plu geif rim lil echiph e lsiseef a contact ghembeif, ushallyi-en edg -a ,,"sty1u s; i cehnectifen with ing mamas;manned 1111011 eeres v I01:- blzrde' and eesoci atec l. with e Siy st hflef plied, the'two styh'heingedapted t cker;

of each division by observation of its position to a fine degree by means of its multiplying devices which may function in associationwith a marked Zero point and this having been done the position of the other stylus relatively to the zeroizing stylus may be bserved by means of its movement multiplying devices which are associated with a graduated or calibrated scale.

The manner in which the invention may be practiced is hereinafter more particularly 7 described with reference to the accompanying diagrams in connection by way of example with a toothedwheel and by the use of two styli. Figure 1 is a diagrammatic 'view of the styli with their adjuncts and a portion of the toothed wheel being dealt with.

'views at right angles to each other illus- Figlll'es l and 1 are elevational trating the manner of mounting of the styli on theresilient plates or blades. Figure '2 is a diagram of the hypothetical rate of change of error in the pitch of the teeth of a toothedbwheel of fifteen teeth and Figure 3 is a diagram of true error produced or plotted by calculationfrom the diagram Figure. 2.

a, b are the two styli each mounted as usual upon aresilient plate or blade 0 anchored below the stylus and admitting of move mentof the stylus against resilience in di rections acrossits axis as well as in the direction ofits axis. The styli have rounded acting extremities so shaped and of such stylus and lever.

moved 1n directions across its axis against.-

size as to engage in the spaces between the teeth and bear against the sides of the'teeth at about the pitch circleso that eachst-ylus adjusts itself to the middle of a space or recess between two teeth, which middle may be regarded as the beginning of one division of the pitch circle and-the end of another division. Each stylus is associated with a system of movement multiplying levers 0 0. In each system one lever is rigidly connected with the stylus so as to move therewith and is jointed at its rear "end to a horizontal strut or connecting member 0 which at its other end is jointed to the rear end of the other lever c of the system which is pivoted at 0 The lever '0 which moves directly with a stylus is supported by a pin pointed strut c which although it prevents that lever c sagging does not interfere with the movement of the Each stylus may be movement is communicated through the member 0 to" the rear end of the other lever of the system but as this lever is pivoted much nearer its rear end than to the point er at its other end, the movement of the rear end of thelever is again more multiplied in the movement ofthe pointer. In

each system therefore the movement of the pointer caused by lateral displacement of the stylus is very much greater than. that lateral movement. This should be well understood as a single stylus mounted on a resilient blade and connected with two movement multiplying levers'as described is known in the art of gauging ortesting. Thefstylus a acts asthelocating. device hereinbefore rev ferred to and the free end 0 of its system of multiplying levers actstin association with afixed marked zero (Z. The other stylus 7) acts as the indicator of comparative variation if any, in the divisions of the pitch circle and the free end 0 of ItS S VStGIU of mult1ply1nglevers acts in association with a graduated 'or calibrated scale 6 having a marked zero 6. In dealing with the hypothetical'example' indicated the styli are allowed to enter two adjacent recesses in the work, their resilient mounting causing them to bear against the sides'of the teeth and the i work which is temporarily mounted on' a rotary mandrel or spindle indicated at f is adjusted until the pointer c is-at the zero c2 and the position of the pointer c in relation to the Zero 6' is observed and noted. 'A point 1 (Figure 2) is then marked: on. say.

squared paper and in any convenient position as its position is not dependent on the observation referred to. The work is then turned and the styli caused'to'enter the recesses respectively adjacent to those'in which the styli were formerly engaged, that is. the

stylus on then engages in the recess in which the stylus Z9 was first engaged.

zero and the position of the pointer 0 in relation to its zero and its former position is observed. The squares of the squared paper are assumed to be proportionate at some convenient rate to the markings on the scale 6 and a point 2 is marked at a distance above or below the point 1 proportionate to the distance between thefirst and second positions of the pointer 0 the point 2 being marked above or below the point 1 according to whether the second dimension observed is greater or less than the first dimension. In the example shown thepoint 2 we been made on the same horizontal linens the point 1 indicating'that the seconddimension'was found to be the same as the first. This procedure is adopted for the third, fourth and subsequent dimensions indicated by the points 3', lon the diagram until the last, the fifteenth, is observed and indicated by the point 15, it being understood that the position of every "point 8X- cept the first is located according to the position of the point previously marked and The work j is again ad usted until the pointer c is at the hoe seal e e betfieen tio'nsflof the pointero The lateral d equ t s; hat S,

tejneslhetiwfeeh the points are not materral zt'jid ahy c'on'veniel lt unit the? he tah'eii for this feature of the plotting, The points ere then ronneeted by lines except that nate's. This maybe done by an equetioh as h w the zeroor ZifOlillQ OiE e11 thepoints to define the 'valueofthe' Qlus' anddhums 0rd;-v

ih it he rate of change of error ourv e of any;

ehdle'ss or closed series ofl d ivisiofisfthe v 'e r' ht squares above he zero hne. Aecorcl stiih of the ordihetes of an the points above such a zero linemust equal thefsurnjof the.

ordinates below. Thus if the distenee from the poihtLfron; thefzlero line is w in terms e s n; v t v. v M r ,7 pornt 1 and thehroken hne e drawnfhetween rthe poifits" lgandf15 across the zero line part being-shown on one sideof the diagram from the 1fite. of reharigel of error. diagram is shownvih Fig'ure 3,; The diagramiis corrifi'leneefl m a point oh the Zero line one major sqti'zire to the left of the position to be 7 point ofcommeneement. of the diagram and 4 I o 2 i else in error tothe same gr ee, threfore in Figure 3 pornt gh ls one 'h f aqor squereito the rlghtfend tito'rntijor squares ebove poiht 1 The next (Qimensjofiffoih 2: 3 hirsfeii error of plus units, t is two 'unitsgmor the errorofldirhensioriI to 2;; The point 3 in 'F igttre 3 is theiefore' plo above the p i;nt1.2,s 1b tih g the point 3 lngfto Fig dre 2 thfe'herit"dimension3 to 7 hate of v The zero lhi e may theretoreihe drawn.

two ma or squares beneath the t v el 'l lld ee e e?" p wen to'point 1' the distance between the point" 1' represeiitihg the first dimension giu'tged. As the diagram Figure 211s directly bzis'ed onen chplotted in accordance "th theverilzitions of thevariohs individual dimensions compared one with the other the rdistance ofjany of the points 1, 2, 3,

from the zero line indicetes the error in thefertieiilar diiherision the termination of which is indicated by the particular point, those above. the zero hne hemg plus errors and those belowbe ng mmus errors. The

true: errorhdjegrtm l tohe .produeed must 'howetef, clearly indicate the plusrorirninu s error zit afiy 'pointfromhhy selected point in the series of dimensions and it' is clear therefore that to produce such a true error (hugrami'rom a rateiof ehel lgeof-erroi' die- 4 gram, the error in'ea ch dimension must be v add dvor subs'traet'ed (as the case may be) to or from ,the error or balance of plus or,

minus errors atthebeg'i n fi lhg ofithat dihd'en s'lon, From thechagram F1gu1e'21it'is ob or chan e; tom zeroiit'o 'ltis two major H e ur'iits ohthef-mihos side of he zer fii hflfi .5, h im'e s e i 3Wto seven units 0 smalle In the dlagralm s an ma r uares. beneath the polnt.

4 correc ififthe point 15 being on the ew 1 lie? 1S0 e? if ,i h' res .e ein t proves c orreet therate of error, dlagrztm and not then' it lSi known that'thet'diagran1 is incorre'et. .Thg diagram of rate Of chahg'e e1'ro1 (-F 1"gu're trhe: error (Fig? v1 0.0

compared onew th the other for the gree- ,3) a e; of eo fire, very differenti n form so s that willfh ejztpperent fronithe forego- .aii efee 4 i Pla e V ihg', becausewhih poiht's} 11 re 2 s 10;. nii nus err or hi the p'nrtiedler 'chmeh the "terihinet'ioh o f tiforr f t e poixits i nFig1ire 31 esfcomp'alred ivlth thenzeljolihe .ijidiezitesth e plus 03- lhihus erifoigoi thepoihts t e-om the beginhi iig of the dimension the eliid' of which ;is -ii1diated 1 'shown in thegdiegram lg'ure The chagram'F gure 2 s howsth at the dillh ensf 1n 2&0 Eris two units. greater 'Qdi-rpriisidhl to 2,.ahtL.therefore, elffgm units too greet, but the di- I I to 2 was z flso two units too great, 5 also qe' dirnehsioh zero tol, consequently the 'i'ol 3" eight u li its 'iSplQoeeLQhth P $1645 f m: t ee n ng-eifill dimes were sham inieure '8 Where pomt 3 1s eight units above the Zero ihdi'e ted hyr-tthe poliht tl le looa-y rt 1; In the' hypothetiea" ezise described and s, therefore that the" eiid of d'iline. Then taking the dimension 3 to 4; thi is shown by Figure 2170 be eleven units smaller than the dimension 2 to 3, but the dimension 2 to 3 ivas four units too great, therefore the dimension 3 m4 is in itself seven units too small as indicated in Figure 2 where the point 4 is seven major squares below the zero line. As therefore point 3 is eight units on the plus side from the beginning of the dimensionzero to 1, it is obvious that the minus error in the dimension 8 to 4: reduces the total error to one unit on the plus side and this is indicated by Figure 3 from which it will be observed that point at is one major square above the It is hardly necessary to continue with this comparison of the two dia Zero line.

grains and it will be r alized that each point in the diagram Figure 3 is nearer to or farther flOlll tl'lfi zero line according to the total previous error or balance of. preceding plus and minus errors; For instance, in Figure 3, the point 9 is actually on the Zero line showing that notwithstanding the errors in the previous dimensions they compensate each other so that the end of the dimensionS to 9' is actually in correctposition, although this would not be directly apparent from Figure 2 which merely shows that the dimension. 8 to 9 is five units smaller than the dimension? to 8 and is itself one unit too large. If the relationship of proportional'movement between the pointer c and lateral movement of the stylus b be known then the diagram will indicate the actual rate of change error and true errors in the pitch respectively.

VJhen the divisions of agraduated dial or circular scale are to be gauged or tested according to the present invention it is convenient to use two microscopes in a manner which will beunderstood from the foregoing descriptionand by the known manners ofuse of microscopes for gauging-or testing. In practising the present invention one microscope is provided with a zero hair line and the other either with a gradicule in the eye piece or a hair line adjustable by a ii'iicrometer. The degree of multiplication provided for of the movement of the styli or the power of the inicroscopesis according to the clegree of accuracy desired and for example by providing optical magnification of the movement of the pointers 0 c in known manner an inaccuracy of division of .000005 of an inch may be possible of detection.

The present invention is particularly valuable in the production of toothed wheels and worm wheels and the like. After the first formation of the teeth or the like the pitch thereof is gauged or tested as hereinbefore described and steps taken to reinedythe errors'as for instance by lapping or the like and then the work may be submitted to a .ing operation and so on until the pitch or dimensions of the divisions are found to be perfect. When the invention is used in con-.

nection with such articles as divided circulai' scales or dials the errors, if any, between the divisions having beeiiascertained according to the invention the various small errors may betaken into account in using the scale or dial, or the scale or dial may be used as a master scale or dial and perfect ly divided scales or dials may be produced by taking into account the errors in. the master.

In some cases it is desirable to provide means for checking the result by dealing with certain equal portions or proportions.

of the whole series of divisions dealt with, that is, in {P591185 having an even number of divisions four or other equal portions: or

ill the case of a series having an odd number of divisions three equal portions, or some other number of equal portions into which the whole series of (llVlSIOHS may be'dlVldE Cl.

For instance in the case of a series of360- divisions it 11 iy in some cases be advisable after the true error curve has been obtained to check also the 90, 180.. 270-and 360 depoints as if it were a four division plate or a s ries of four equal divisions. This checking would obviate any slight progressive error occurring without being discovered. V r r in the case of toothed wheels and some other articles it is more important in connection with the desired accuracy of the divisions or pitch to ascertain the rate of ClRLDgB Of QIIOI than the true error curve because it is the rate of change of error ti-Ii lUS which causes the objectionable acceleration and the use of the present invention enables the rate of change of error diagram to be produced directly which is an advantage. For work-shop practice this rate of'change of error diagram is usually sufiicient but where it is desired to obtain the true error curve this maybe readily made by calculation from the rate of change of error diagram or curve as hereinbefore set forth.

The invention is specially useful in. connection with toothed wheels or worm wheels or division of a circular scale or. dial or dividing head or plate but the invention may also be used in connectio'nvwith any divisions in an endless series. I

What I claim and desire to secure by Letters Patent of the United States is 1. A method of gauging ortesting accu-. racy of the division of an imaginary or actual circle of other endless line on or in an article into parts or divisions intended to be equal consisting essentially in zer'oizing the beginning of a division and noting the limit 2. A method of or termination of its dimension for purpose ofif lOlnptl isOll, :zeroizing the begimi'li act the next succeeding division to the same i zero an'dthen vaseentaining."thedegree of variation, :if any, of itliedimension of that d ion as. compared with the dimension to" preceding division and performing this 10p;

eration on eachoithe other ;divisions in succession and thus ascertaimnp; :the iate of "change oferror throughout the seriesot divisions. V p gauging ontcsti ng accuracy or the division or an imaginary or actual circle or other endless line on or in an article'into parts orv divisions intended to be equal consisting; essentially in zeroizing the beginning of a division and noting the' lim t or termination of ts dimension for purposes of coinparisongzeroizing the beginning of the next succeeding division to the same zero and then ascertaining the dethe true error throughout the series from the data ofthe rate of change of error.

. 3. A inethodof gauging or testing accuracy of the division of an imaginary or actual circle or other eiidlessiline'on or in an article into parts or divisions ntended to be equal consisting essentially in 'Zeroizing'the beginning of a division and noting the limit or termination of its dimension for purposes of comparison, zeroizing the beginning of the next succeeding division to the same zero and then noting the degree of variation, if any, in the dimensionof that Cll-VlSlOI] as compared with the dimension of the preced- V ing division and performing this operation on each of the other divisions'in succession recording the results of comparison byre-v cording indications-in relative positions according to the var ations in 7 dimensions ascertained and-obtaining the location for theizero line of said indications by equating the sums-of'the ord nates algebraically calculated above. and below the zero-line; 9

4. A method? of gauging or testing accuracy of the 'divisionoi airimaginary or actual circle or other endlessline on or in an article into parts or divisions intended to be equal consisting essentially in zeroizing the. beginning ofa division and noting the limit 'or termination of its dimensions for purposes;-

of comparison, zeroizing thefbe'ginning of the next succeeding division to the same zero 7 and then noting the degree of variation, if

any in the dimension of [that division as compared with the dimension oft-he preceding division and performing this operation on each of the other divisions in succession "cording indications in :relat I v cording to the variations 71'11 'Cl];111 nsi s as-f ceritained, obtain ng the location to zero line of said indicat'ionsxby equating the su i' s oi the ordinates algebraically ical'c above andfbelow the zero 'gline an obtainingaan indication or diagra t fichetrue error from the recorded-:indic-a ons of the rate of change'ot error and the ascertamed location for the zero line aforesaid.

5. method of gauging or testing'the uni- "forinity in pitch lirouglioiit an-endless or closed series of recesses in'an article, consisting essentially in zeroizing; the beginning of a pitch by the use of a contact memberwhich is caused to locate in one of the said recesses and makecontact with both sides thereof and noting the limit or termination of that pitch for purposes of comparison by the use of another contact member which is'caused to locate in the neXtrec-ess and'make contact ;with both sides thereofizeroizing the beginning of the next succeeding pitch by causing the first mentioned contact member to locate in i ql'ited in thelast mentioned recess and ascertaining the degree of, variation, if any, of the apitch' as compared with the preceding pitch'by causing the second mentioned contact meinher to locate in the next recess and performing this operation oneach other pitchin succession andthus ascertain therate of change of error in the pitch throughout the series of recesses. i 6. An instrument or cesses or projections in or on'a'n article co nprising in combination amember displaceable to and from the work to' engage the work at each side of one recess or PTOJQC- tion to zeroize it, another member displaceable to'and from the work to engage the' work at the same tiineat each side of another recess or projection and laterally displaceablerto and from the first mentioned member, and a ,device to indicate in a inulti plied manner variations in its distance from the first mentioned member. V

.7. ,An instrument or apparatus gauging ortesting the uniformity in the pitch of an endlessor closed series of recesses in oron an article, comprising in comapparatus for use in I v gauging or testing the uniformity in the- -p1tch. ,0f an endless or closedseries of refor use in l bination two. contact members for engaging in the recessesinf'succession and capableof displacement to. and-from the work, one of said contact membersbeing foruse in zeroizing the beginning 'of eachpitch and the other contact member being laterally displaceableito' and from the first mentioned contact member, each of said members mak V 'ing'contact with opposite sides'of a recess gan'd a device to indicate in a multiplied manner, any variation i i-its distance from the first mentioned, contact member and thus here for engaging in said recesses in suc'cesdisclose any variation in the dimension of a pitch as compared with another.

8. An instrument or-apparatus for use in gauging or'testing the uniformity in the pitch of an endless or closed series of recesses in or on an article, comprising the combination of means to support thearticle and admit of its rotation, two contact mem sion, two resilient plates or blades each carrying one of the said contact members and admitting of displacement of each memher to or from the Work and also lateraldisplacement of their extremities relatively to each other, and a device to indicate in a multiplied manner any variation inthe distance between the said members.

AXEL CHARLES WICKMAN 

